Method of attaching an implant to an impactor

ABSTRACT

A method and apparatus for implanting acetabular components into an acetabulum utilizing a minimally invasive incision. The method and apparatus utilize a subatmospheric pressure formed in a hollow passage of an elongate body to secure an acetabular shell to a shell-engaging head removably attached to a coupler end of the elongate body. Liner-engaging heads may also be removably attached to the coupler end to install socket liners into an implanted acetabular shell. The elongate body may comprise a bent portion to allow access to the acetabulum through a minimally invasive incision.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/534,431, filed Jan. 5, 2004, and U.S. Provisional Application No.60/541,344, filed Feb. 2, 2004, which applications are herebyincorporated by reference herein in their entireties, including but notlimited to those portions that specifically appear hereinafter, theincorporation by reference being made with the following exception: Inthe event that any portion of the above-referenced provisionalapplications is inconsistent with this application, this applicationsupercedes said above-referenced provisional applications.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

BACKGROUND

1. The Field of the Invention

The present disclosure relates generally to surgical instruments, andmore particularly, but not necessarily entirely, to an apparatus andmethod for implanting surgical prostheses during surgery.

2. Description of Related Art

The number of total hip replacement surgeries has increased dramaticallyin recent years. Hip replacement surgery involves implanting aprosthesis to replace an ailing hip joint. The prosthesis is typicallymade up of two parts: an acetabulum component, or socket portion, whichreplaces the acetabulum and a femoral component, which replaces thefemoral head. The acetabulum component may in turn comprise a metalshell, hereinafter referred to as an acetabular shell, with a plastic orceramic inner socket liner, hereinafter referred to as a socket liner.

The steps for replacing the hip begin with the surgeon making anincision over the hip joint. There are several different approaches usedto make the incision, usually based on the surgeon's training andpreferences. After the incision is made, the ligaments and muscles maybe separated to allow the surgeon access to the bones of the hip joint.Once the hip joint is entered, the femoral head may be dislocated fromthe acetabulum. Then the femoral head may be removed by cutting throughthe femoral neck with a saw. After the femoral head is removed, thecartilage may be removed from the acetabulum using a power drill and aspecial reamer. The reamer may be used to form the bone in ahemispherical shape to exactly fit the acetabular shell of theacetabular component. Once the right size and shape is determined forthe acetabulum, the acetabular shell may be inserted into place. In theuncemented variety of artificial hip replacement, the acetabular shellmay be simply held in place by the tightness of the fit or with screwsto hold the metal shell in place. Insertion of the acetabular shell maybe done by hand or by use of a hand tool that grips the shell. Often,the surgeon may set the acetabular shell into the acetabulum byimpacting it through the use of a mallet and an impaction device. Thesurgeon may then insert a socket liner into the acetabular shell. Oncethe acetabular shell and socket liner are in place, the surgeon may thenreplace the femoral head with a femoral component and the surgeon mayreassemble the hip joint. The surgeon may also test the movement of thehip joint before closing the incision.

One of the major difficulties confronting the surgeon during hipreplacement surgery is the relatively inaccessible location of theacetabulum making it difficult for the surgeon to correctly position theacetabular components. In the past, the solution has been to make arelatively large incision to allow the surgeon complete and unfetteredaccess to the hip joint. However, from the patient's perspective, alarge incision is undesirable as it increases the trauma to the patientand the recovery time.

Attempts have been made in the previously available devices to provide ahand tool to assist in holding and positioning an acetabular shell. U.S.Pat. No. 5,116,339 (granted May 26, 1992 to Glock) discloses aninstallation tool having an expanding head for engaging the acetabularshell. The acetabular shell is released by contracting the head when theshell is in position. The head is expanded and contracted by means of athreaded shaft with a knob such that rotation of the knobcorrespondingly expands or contracts the head. U.S. Pat. No. 4,305,394(granted on Dec. 15, 1981 to Bertuch) discloses an acetabular shellpositioning device comprising an interchangeable ball and flange forengaging the inner cavity of the acetabular shell by a mechanicalengagement. A coupling rod with a handle is manipulated in order toengage and release the acetabular shell.

U.S. Pat. No. 3,859,992 (granted on Jan. 14, 1975 to Amstutz) disclosesa suction-operated holding and positioning instrument for use ininserting an acetabular shell during hip surgery. The Amstutz deviceincludes a permanently affixed shell-engaging head and an externalsuction source for forming a suction force between the shell-engaginghead and the shell. The Amstutz device further provides a portcontrolled by a mechanical valve for selectively breaking the suctionforce formed between the shell-engaging head and the shell. The Amstutzdevice does not appear to be able to be used with cementless acetabularshells that require impaction.

The above devices are characterized by several disadvantages includingcomplicated designs involving several moving parts that both increasemanufacturing costs as well as making the device more difficult to useduring an operation. In particular, the Amstutz device disadvantageouslyrequires a connection to an external suction source. The Amstutz devicefurther does not allow for interchangeable shell-engaging heads to allowthe device to be used with different sized acetabular shells. Finally,it appears that none of the above devices can be used to both implant anacetabular shell and a socket liner.

In addition, the shape of the devices dictate the use of relativelylarge incisions during surgery. One attempted improvement over thepreviously available devices to reduce the size of the required incisionis disclosed in U.S. Patent Publication Application 2003/0229356(published Dec. 11, 2003 to Dye). The Dye apparatus includes a curvedimpaction instrument for aligning and impacting the acetabular componentinto the acetabulum. The curved shape of the apparatus allows for aminimally invasive incision in the patient.

Similarly, U.S. Patent Publication Application 2003/0050645 (publishedMar. 13, 2003 to Parker et al.) discloses a curved impactor having ahollow outer shaft and a flexible drive shaft disposed in the outershaft. The flexible drive shaft is connected at one end to a coupler,and at the opposite end is a thumb wheel, such that rotation of thethumb wheel rotates the drive shaft and engages the coupler to anacetabular shell.

Unfortunately, despite their advantages, both the Dye and Parker et al.apparatuses still has several shortcomings. In particular, theattachment of the acetabular shell to the device requires a mechanicalengagement of the shell to the device. Dye is particularlydisadvantageous due to the fact that it does not teach a remote releaseof the acetabular shell once it is installed in the acetabulum. Parkeret al., on the other hand, is disadvantageous due to its overlycomplicated remote release mechanism.

The prior art is thus characterized by several disadvantages that areaddressed by the present disclosure. The present disclosure minimizes,and in some aspects eliminates, the above-mentioned failures, and otherproblems, by utilizing the methods and structural features describedherein. The features and advantages of the disclosure will be set forthin the description which follows, and in part will be apparent from thedescription, or may be learned by the practice of the disclosure withoutundue experimentation. The features and advantages of the disclosure maybe realized and obtained by means of the instruments and combinationsparticularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the disclosure will become apparent froma consideration of the subsequent detailed description presented inconnection with the accompanying drawings in which:

FIG. 1 is an exploded perspective view of one exemplary embodiment madein accordance with the present disclosure.

FIG. 2 is a cross-sectional view of one exemplary embodiment of animpactor.

FIG. 2A is a cross-sectional, break-away view of an alternativeembodiment of the impactor of FIG. 2.

FIG. 3 is an end view of the impactor illustrated in FIG. 2 made inaccordance with the present disclosure.

FIG. 4A is a top view of an exemplary engaging head made in accordancewith the present disclosure.

FIG. 4B is a side view of an exemplary engaging head made in accordancewith the present disclosure.

FIG. 4C is a bottom view of an exemplary engaging head made inaccordance with the present disclosure.

FIG. 5 is a cross-sectional side view of the impactor, shell-engaginghead and an acetabular shell made in accordance with the presentdisclosure.

FIG. 6 is a cross-sectional side view of another embodiment of anengaging head made in accordance with the present disclosure.

FIG. 7 is a cross-sectional side view of still another embodiment of anengaging head made in accordance with the present disclosure.

FIG. 8A is a side view of an exemplary embodiment of a liner-engaginghead made in accordance with the present disclosure made in accordancewith the present disclosure.

FIG. 8B is a top view of the liner-engaging head made in accordance withthe present disclosure.

FIG. 8C is a bottom view of the liner-engaging head made in accordancewith the present disclosure.

FIG. 9 is a cross-sectional side view of the liner-engaging head mountedon the impactor made in accordance with the present disclosure.

FIG. 10 is a perspective view of an exemplary embodiment of an impactorhaving a positioning handle made in accordance with the presentdisclosure.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the principles inaccordance with the disclosure, reference will now be made to theembodiments illustrated in the drawings and specific language will beused to describe the same. It will nevertheless be understood that nolimitation of the scope of the disclosure is thereby intended. Anyalterations and further modifications of the inventive featuresillustrated herein, and any additional applications of the principles ofthe disclosure as illustrated herein, which would normally occur to oneskilled in the relevant art and having possession of this disclosure,are to be considered within the scope of the disclosure claimed.

It is also to be understood that the terminology employed herein is usedfor the purpose of describing particular embodiments only and is notintended to be limiting since the scope of the present disclosure willbe limited only by the appended claims and equivalents thereof.

It must be noted that, as used in this specification and the appendedclaims, the singular forms “a,” “an,” and “the” include plural referentsunless the context clearly dictates otherwise. In describing andclaiming the present disclosure, the following terminology will be usedin accordance with the definitions set out below. As used herein, theterms “comprising,” “including,” “containing,” “characterized by,” andgrammatical equivalents thereof are inclusive or open-ended terms thatdo not exclude additional, unrecited elements or method steps.

Applicant has discovered a simple and easy to use apparatus forpositioning and implanting an acetabular shell into the a patient'sacetabulum during hip replacement surgery using minimally invasivesurgical techniques. Applicant's disclosure may also be utilized toimplant a socket liner in an implanted acetabular shell. Importantly,Applicant's disclosure does not require a mechanical engagement means toengage and hold the acetabular shell during implantation. Instead,Applicant's disclosure teaches the use of subatmospheric pressure tohold the acetabular shell on an engaging head. One aspect of thedisclosure is unique in that an external suction source may not berequired in order to create the subatmospheric pressure. Applicant'sdisclosure may also comprise a valveless and open port sealable by afinger for allowing the subatmospheric pressure to be created and to bebroken, to thereby selectably release the acetabular shell from anengaging head. In addition, another aspect of the Applicant's disclosuremay permit the use of interchangeable engaging heads thereby permittingthe implantation of acetabular shells and socket liners of differentsizes with the same apparatus.

As used herein, the term “minimally invasive incision” means an incisionas is known in the art to reduce trauma in the patient, for example anincision ranging between about two and one-half inches and about fiveand one-half inches. As used herein, the term “pressure-maintainingseal” means a seal that inhibits airflow to a degree sufficient toenable a non-atmospheric pressure to be established and maintained at anon-atmospheric level, whether the non-atmospheric pressure is constantor varies within a non-atmospheric range.

Referring now to FIG. 1, reference numeral 8 generally refers to anacetabular shell impactor assembly pursuant to one embodiment of theApplicant's disclosure. The assembly 8 may comprise an impactor 10 and atool or engaging head, such as a shell-engaging head 18, disposed on theimpactor 10. The impactor 10 may comprise an elongate body 12 extendingfrom a distal end 11 to a proximal end 13. A coupler end 14 and a head16 may be disposed on the distal end 11 and the proximal end 13,respectively. The elongate body 12 may have a hollow passage 54 in itsinterior extending between the coupler end 14 and the head 16 as canbest be seen in FIG. 2, and said hollow passage 54 may be closeable.

Referring back to FIG. 1, the elongate body 12 may further comprise afirst portion 20 extending from the proximal end 13 along a longitudinalaxis 40 towards the coupler end 14. The first portion 20 may besubstantially straight and may be used as a handle by a surgeon duringsurgery to assist in positioning the impactor 10. In particular, asurgeon grasping the handle near the proximal end 13 may be able toplace the thumb of the hand grasping the handle over the port 42 locatedon the top surface 17 of the head 16, in order to seal the port 42 witha pressure-maintaining seal and thereby close the hollow passage 54 whenan implant such as shell 62 is disposed on the engaging head 18.

A second portion 22 of the elongate body 12 may extend between the firstportion 20 and the coupler end 14. The second portion 22 may form a bendin the elongate body 12 such that the second portion 22 may, if desired,deviate from and return to the longitudinal axis 40. The second portion22 may comprise a first segment 23A, a second segment 23B, and a thirdsegment 23C as shown in FIG. 1. The first segment 23A may be connectedto the first portion 20 at an angle such that the first segment 23Adeparts from the longitudinal axis 40. The second segment 23B may beconnected to the first segment 23A. The second segment 23B may besubstantially parallel to the longitudinal axis 40. The third segment23C may be connected to the second segment 23B at an angle such that thethird segment 23C is directed back towards the longitudinal axis 40 inthe direction of the coupler end 14. In one embodiment of the presentdisclosure, the second segment 23B may extend substantially parallel tothe longitudinal axis 40 a distance d, that may be at least 10 percentof a distance d2 extending between the proximal end 13 and the distalend 11 of the impactor 10 along the longitudinal axis 40, as shown inFIG. 1.

The bend in the second portion 22 may be sized and shaped such that thecoupler end 14 can be positioned inside of the patient while the head 16is positioned outside of the patient. It will be appreciated by thoseskilled in the art that the bend in the second portion 22 may allow anacetabular shell to be positioned and impacted into a reamed acetabulumthrough a minimally invasive incision. Further, the bend in the secondportion allows the impactor 10 to be positioned so as not to interferewith other anatomical structures around the acetabulum while theacetabular shell is brought into and implanted into the acetabulum.Further, the bend may allow an almost linear transfer of an impactionforce from the head 16 to an acetabular shell along the longitudinalaxis 40 without disturbing the surrounding anatomical structures.

In will be appreciated that the bend may be located on the impactor 10at different locations along the elongate body 12 to facilitate varyingsurgical techniques. Further, the bend may be curved, elliptical,piecewise linear, or circular in shape with a constant or varyingcurvature. In this regard, it will be appreciated that the secondportion 22 may have alternative embodiments other than then bend asdescribed above. For example, the second portion 22 may be curved, arcedor circular. In some embodiments, the second portion 22 may even bestraight. It should also be noted that the elongate body 12 may be ofmodular or one piece construction. The modular construction may includea combination of linear or non-linear segments. It will be understoodthat the bend and the elongate body 12 may constitute a means forpositioning an acetabular shell into an acetabulum through a minimallyinvasive incision.

As mentioned, the head 16 may be disposed on the proximal end 13 of theelongate body 12. As can best be seen in FIG. 3, the head 16 maycomprise a top surface 17 that may be planar, and an annular rim 24. Thetop surface 17 may be of sufficient size to receive an impaction forcefrom a surgical mallet or the like. The annular rim 24 may protect thehand of the surgeon holding the impactor 10 from missed or glancingblows from the surgical mallet.

In addition, in the center of the top surface 17 may be a port 42 asviewed in FIG. 3. The port 42 may be in fluid communication with thehollow passage 54 in the elongate body 12 as is best shown in FIG. 2.The port 42 may be sized and positioned in the top surface 17 such thata thumb can placed over the port 42 to thereby create apressure-maintaining seal. The port 42 may be situated along thelongitudinal axis 40. It should be noted, that it is within the scope ofthis disclosure that the position of the port 42 may be located anywhereon the head 16 or the elongate body 12. For example, in reference toFIG. 2A, it will be appreciated that a port 42 a may be formed to extendthrough the elongate body 12 in a radial direction, in lieu of port 42in FIG. 2.

The port 42 may be valveless and open. As used herein, the term “open”means in fluid communication with the atmosphere such that theatmosphere may enter the hollow passage 54 through the port 42 when theport 42 is not sealed. Moreover, while it is less desirable, amechanical valve as is known in the art may be used to operate and sealthe port 42, but typically the port 42 may be sealed with the thumb of asurgeon as described above. It will be understood that the port 42 mayconstitute a means for selectively breaking a subatmospheric pressure inthe hollow passage 54.

The coupler end 14 of the impactor 10 as shown in FIG. 1 may be utilizedto removably and interchangeably attach the engaging head capable ofengaging a surgical implant, such as a shell-engaging head 18 or asocket-liner-engaging head 58 (see FIGS. 7 and 8). The coupler end 14may comprise an annular flange 26 extending radially from thelongitudinal axis 40. The side of the annular flange 26 facing away fromthe distal end 11 may form a seat 27 against which an engaging head maybe oriented.

Extending from the middle of the seat 27 along the longitudinal axis 40and in a direction away from the distal end 11 may be an extensionmember 28. The extension member 28 may extend in a substantiallyperpendicularly direction from the seat 27 and may be substantiallycylindrical in shape but it will be appreciated by those skilled in theart that other shapes may be permissible that are consistent with thepresent disclosure.

The extension member 28 may comprise an outer surface having aforward-most annular groove and a rear-most annular groove each of whichare adapted to receive a resilient member 30, such as an o-ring. Anexposed end 31 of the extension member 28 may have a port 32 locatedthereon in fluid communication with hollow passage 54 in the elongatebody 12 as may be observed best in FIG. 2. The port 32 may be centeredon or off of the longitudinal axis 40.

As will be discussed in more detail below, the extension member 28 maybe sized and shaped to slidably and removably engage an engaging head,such as a shell-engaging head 18 or a socket-liner-engaging head 58 (seeFIGS. 7 and 8), by a pressure-maintaining seal. It should be noted,however, that other methods of attaching an engaging head to the couplerend 14 are known to those skilled in the art that fall within the scopeof this disclosure. For example, an engaging head may rotatably engagethe coupler end 14. Also, an engaging head may be permanently mountedonto the coupler end 14. Alternatively, the engaging head and theimpactor 10 may be constructed as a one-piece unitary member. Moreover,with respect to the resilient members 30, a pressure-maintaining sealmay be formed by using either a single resilient member 30, or a pair ofresilient members 30 as shown most clearly in FIG. 2, or some otherplurality of resilient members 30, may be positioned in a variety oflocations either on the engaging head or the coupler end 14 as is knownin the art to facilitate the formation of a pressure-maintaining sealbetween the coupler end 14 and the engaging head. Further, it will beappreciated that the resilient members 30 may not be required at all forachieving the pressure-maintaining seal. It will be understood that thecoupler end 14 may constitute a means for selectively engaging any oneof a plurality of engaging heads by a pressure-maintaining seal.

A cross-sectional view of the impactor 10 is shown in FIG. 2. Aspreviously mentioned, the hollow passage 54 extends from the distal end11 to the proximal end 13 of the elongate body 12 through both the firstportion 20 and the second portion 22. Port 42 may be positioned in thetop surface 17 of the head 16 and may be interconnected with the hollowpassage 54 by a fluid communication path 43. Likewise, port 32 may bepositioned in the exposed end 31 and may be interconnected with thehollow passage 54 by a fluid communication path 33. In addition, port 42and port 32 may constitute the only egresses from the hollow passage 54.It will be observed, that both port 42 and port 32, as well as fluidcommunication paths 33 and 43 may lie on the longitudinal axis 40.

The size of the ports 42 and 32 may be smaller than that of the hollowpassage 54. As explained above, port 42 may be configured and sized suchthat it may be sealed by a thumb of a surgeon. As will be explained ingreater detail below, port 32 may be configured and sized to align witha fluid communication path in an engaging head. Typically, fluidcommunication path 43 is through the head 16 while fluid communicationpath 33 is through the coupler end 14. It will be appreciated, however,that it is a feature of this disclosure that the ports 42 and 32 may bepositioned anywhere along the impactor 10. It will be understood thatthe hollow passage 54 may constitute a means for forming asubatmospheric pressure.

Annular flange 26 may extend radially from the longitudinal axis 40while extended member 28 may extend parallel and along the axis 40 awayfrom the distal end 11. Seat 27 and exposed end 31 may be perpendicularto the longitudinal axis 40. Resilient members 30 on the extended member28 may be radially positioned from the axis 40.

FIGS. 1, 4A, 4B, and 4C show an isometric view, a top view, side viewand a bottom view, respectively, of one embodiment of the shell-engaginghead 18 which, as mentioned above, may be removably attachable to thecoupler end 14 of the impactor 10. The shell-engaging head 18 maycomprise a base portion 48 and a tip portion 34 extending from a surface50 of the base portion 48. The tip portion 34 may be substantiallypartially spherical, such as a substantially hemispherical. The tipportion 34 may extend such that is substantially centered on the surface50 of the base portion 48.

The tip portion 34 may further comprise an annular groove 35 on itsouter surface 37 that may be adapted to receive a resilient member 36(not shown in FIGS. 4A, 4B or 4C), such as an o-ring. A port 38 may bepositioned in the outer surface 37. Located in a rearmost portion 52 ofthe base portion 48 may be a recessed portion 46 having a port 39 influid communication with port 38 on the outer surface 37.

Looking now to a cross-sectional view of the engagement of the engagingmember 18 and the coupler end 14, the recessed portion 46 may slidablyengage the extended member 28 as shown in FIG. 5. The rearmost of theresilient members 30 on the extension member 28 may engage an annularlocking grove 44 formed in a side wall 47 of the recessed portion 46 inorder to form a friction fit to hold the engaging member 18 on thecoupler end 14. The frontmost resilient member 30 on the extensionmember 28 may also engage the side wall 47 of the recessed portion 46which may provide an additional seal as well as a friction fit to holdthe engaging head onto the coupler end 14. It will be appreciated thatthe engagement between the rearmost of the resilient members 30 and thelocking groove 44 may also form a pressure-maintaining seal.

The rearmost portion 52 of the base portion 48 may abut directly againstthe seat 27 of the annular flange 26 when the shell-engaging head 18 isinstalled on the coupler end 14. This interaction may serve to properlyorient the shell-engaging head 18. Likewise, the exposed end 31 of theextension member 28 may abut against a bottom portion 56 of the recessedportion 48.

It will be observed that when the shell-engaging head 18 is properlyinstalled onto the coupler end 14, that port 32 is in alignment andadjacent with port 39 such that port 38 is in direct fluid communicationwith the hollow passage 54. In this regard, the fluid communication path33 may be interconnected with a fluid communication path 60 extendingfrom port 38 to port 39.

In the above described arrangement, the shell-engaging head 18 may beremoved from the impactor 10 by using sufficient force to pull it off.It will be appreciated that the force to pull off the shell-engaginghead 18 should be such that it can be done by an average strength humanbeing as it may be necessary during surgery to replace theshell-engaging head 18.

It will also be noted that an engaging head may be disposed on theelongate body in a modular or integral manner. It will be appreciatedthat if the engaging head is disposed on the elongate body in anintegral manner, that a coupler end 14 is not needed and the engaginghead may be disposed directly on the distal end 11. Alternatively,modular embodiments of the engaging head may have an interveningstructure, such as the coupler end 14, between the engaging head and thedistal end 11. It is to understood that the phrase “disposed on,” whenused in reference to the engaging head being disposed on an object (suchas the distal end of the elongate body 12), means that the engaging headis held in relation to said object either in a modular or integralmanner, either directly or indirectly. Referring now specially to FIG.5, the forgoing definition of the engaging head being “disposed on” anobject, includes the concept that the engaging head 18 is disposed onthe distal end 11 of the elongate member 12, because said engaging head18 is held in relation to said distal end 11, even though engaging head18 and distal end 11 are not in any contact, but are intercoupled by thecoupler end 14.

FIG. 5 also illustrates the engagement of an acetabular shell 62 havingan outer surface 64 and an inner surface 66 with the shell-engaging head18. A rearmost portion 68 of the shell 62 may abut against the surface50 of the shell-engaging head 18 when the tip portion 34 is insertedinto shell 62. Resilient member 36 disposed in groove 35 on the outersurface 37 may form a pressure-maintaining seal with the inner surface66 of the shell 62. An enclosed region 70 may be defined by the innersurface 66 and the outer surface 37. The enclosed region 70 may be influid communication with the hollow passage 54 and may be substantiallyairtight.

FIGS. 6 and 7 illustrate alternative embodiments of engaging headsindicated by reference numerals 100 and 120, respectively. In FIG. 6,the engaging head 100 may comprise a base portion 102 having a surface106 and a rearmost portion 104. A tip portion 110 may extend from thesurface 106. The tip portion 110 may comprise at least one frustoconicalportion 113 having two resilient members 111 disposed in annular grooves116 for forming a substantially airtight enclosed region with an innerportion of an acetabular shell. It will be appreciated that the enclosedregion may be between the two resilient members 111. Ports 114 may bepositioned between the two resilient members 111 and be fluidlyconnected by a fluid communication path 118 to a port 112 located withina recessed portion 108. As before, the recessed portion 108 may have alocking groove 109 to engage the extension member 28 of the coupler end14 as was described above and is incorporated here by reference.

FIG. 7, illustrates an engaging head 120 that may be similar to that inFIG. 6, except that there may be only a single resilient member 126 inan annular groove 127 formed in the tip portion 121. Ports 128 may befluidly connected to port 130 in the recessed portion 122 by a fluidcommunication path 132.

In will be appreciated that embodiments of engaging heads may includevarious configurations all of which fall within the scope of the presentdisclosure. Some of these various configurations may include, withoutlimitation, some of the following features in any combination: a tipportion having one, two or three resilient members in its outer surface,one, two or three ports in the recessed portion in fluid communication,either individually or in combination, with one, two or three ports inthe outer surface, one, two or three ports located in the outer surfacedisposed at any location on the tip portion, and a tip portion having apartially spherical shape, substantially hemispherical shape, a shapehaving one or more frustoconical portions, or any random shape fittingwith a inner portion of an acetabular shell or implant.

It will be appreciated that the various embodiments of the engaging headenable the Applicant's disclosure to be utilized with the numerousvariations in the structure of acetabular shells on the market today ormay be on the market in the future. For example, some acetabular shellsmay comprise screw holes for anchoring the shell into the acetabulum. Anappropriate embodiment of the engaging head consistent with Applicant'sdisclosure may be able to engage that shell as described herein.

Once the shell-engaging head 18 has been installed on the impactor 10 byan engagement with the coupler end 14, it may then be used to positionand impact the acetabular shell 62 into the acetabulum of a patient atthe appropriate time. The acetabular shell 62 may be held onto theshell-engaging head 18 by a subatmospheric pressure formed in the hollowpassage 54. In one embodiment, the subatmospheric pressure may be formedby placing the acetabular shell over the tip portion 34 of theshell-engaging head 18. The resilient member 36 on the outer surface 37may airtightly seal an enclosed region defined by the outer surface 37and an inner surface of the acetabular shell. It will be appreciatedthat at this point, the hollow passage 54 may have only one otheregress, the port 42. The surgeon then may place his or her thumb overthe port 42 located on the head 16.

When the port 42 is initially sealed by the surgeon, the hollow passage54 is substantially airtight and it will be observed that the airpressure inside of the hollow passage 54 may be equalized with theatmospheric pressure for a brief period of time. Due to theconfiguration of the shell-engaging head 18, a subatmospheric pressuremay be formed when the acetabular shell attempts to move away from theshell-engaging head 18, or vice versa. This may be due to that fact thatno outside air can enter the hollow passage 54 while the volume of theairtight region is being increased. It will be understood that as usedherein, reference to movement of a portion of the impactor assembly 8with respect to the shell or implant includes situations in which theimplant remains stationary and the impactor assembly 8 moves, orsituations in which the implant moves and the impactor assembly 8remains stationary, or situations in which both the implant and theimpactor assembly 8 move with respect to each other.

It will be appreciated that the movement of the shell away from theshell-engaging head 18 may be unobservable to the human eye. Once thesubatmospheric pressure has been formed, the surgeon can then properlyposition the acetabular shell in the acetabulum using principles andtechniques that are well known in the art and will not be recited here.Once the acetabular shell is in the correct position, the thumb may beremoved from the port 42 and the pressure inside of the hollow passage54 may again equalized with atmospheric pressure thereby releasing theacetabular shell. A surgical mallet may then be used to implant theshell into the acetabulum by striking the head 16 of the impactor 10.

It will be observed that the prior art is devoid of acetabular shellimpactors utilizing a subatmospheric pressure to hold an implant withoutmoving parts. Moreover, the prior art only teaches the use of anexternal suction source having a permanently fixed engaging head. Inparticular, it is observed that the Amstutz patent does not teach orsuggest that a subatmospheric pressure may be formed by the interactionof the engaging head and the implant, i.e., the movement of the engaginghead away from the implant.

A side view, top view, a rear view of a liner-engaging head 150 areshown in FIGS. 8A, 8B, and 8C respectively. The liner-engaging head 150may be used to install a socket liner 157 (see FIG. 9) into an implantedacetabular shell using the impactor 10 by engaging the socket portion ofthe socket liner 157. It will be appreciated that the socket liner 157may be formed in various different sizes and configurations known in theart, and the liner-engaging head 150 may be configured to be compatiblewith the socket liner 157. The liner-engaging head 150 may comprise atip portion 151 that may be partially spherical in shape. As mentioned,the tip portion 151 may be configured and sized to fit within the socketof the socket liner 157. The tip portion 151 may be resilient in natureto form a friction fit with the socket liner 157.

A base portion 152 of the liner-engaging head 150 may have a rearmostportion 155. Relief grooves 158 may extend from the forward most portion153 towards the rearmost portion 155. In one embodiment, four reliefgrooves 158 may be used. However, it will be understood that any numberof relief grooves 158 may be used within the scope of the presentdisclosure. A port 160 may be positioned in the forward most portion153. A recessed portion 156 configured to engage the extension member 28of the coupler end 14 may extend from the rearmost portion 155 towardsthe forward most portion 153. A port 162 may be located in the recessedportion 156.

Looking now to a cross-sectional view of the engagement of theinsert-engaging head 150 and the coupler end 14, the recessed portion156 may slidably engage the extended~member 28 as shown in FIG. 9. Theforward most of the resilient members 30 on the extension member 28 mayengage an annular locking grove 164 formed in a side wall 166 of therecessed portion 156 in order to form a friction fit to hold theinsert-engaging member on the coupler end 14. The rearmost resilientmember 30 on the extension member 28 may also engage the side wall 166of the recessed portion 156 which a friction fit to hold theinsert-engaging head 150 onto the coupler end 14.

The rearmost portion 155 of the base portion 152 may abut directlyagainst the seat 27 of the annular flange 26 when the insert-engaginghead 150 is installed on the coupler end 14. This interaction may serveto properly orient the insert-engaging head 150. Likewise, the exposedend 31 of the extension member 28 may abut against a bottom portion 166of the recessed portion 156.

It will be observed that when the insert-engaging head 150 is properlyinstalled onto the coupler end 14, that port 32 is in alignment andadjacent with port 162 such that port 160 is in direct fluidcommunication with the hollow passage 54. In this regard, the fluidcommunication path 33 may be interconnected with a fluid communicationpath 168 extending from port 160 to port 162.

Like the shell-engaging head 18, in the above described arrangement, theinsert-engaging head 150 may be removed from the impactor 10 by usingsufficient force to pull it off. It will be appreciated that the forceto pull off the insert-engaging head 150 should be such that it can bedone by an average strength human being as it may be necessary duringsurgery to replace the insert-engaging head 150.

After an acetabular shell has been implanted as described above, thesurgeon may then remove the shell-engaging head 18 from the impactor 10and install an appropriately sized liner-engaging head 150. The surgeoncan then attach the socket liner 157 to the liner-engaging head 150 byinserting the tip portion 151 into the socket. The tip portion 151 mayengage the socket by a friction fit. The socket liner 157 can then bepositioned and implanted into the previously implanted acetabular shell.This may require an impaction force delivered to the head 16 by asurgical mallet. It will be appreciated that the head 16 may constitutea means for receiving an impaction force.

Once the socket liner 157 has been implanted into the shell, the socketliner 157 may then be disengaged from the liner-engaging head 150 sothat the impactor 10 may be removed. The relief grooves 158 prevent andport 160 reduce the hydraulic suction that is sometimes generatedbetween the liner-engaging head 150 and the socket liner when synorialfluid or another fluid is present. It will be appreciated that otherembodiments of insert-engaging heads may be possible that fall withinthe scope of the present disclosure. Moreover, it will also beunderstood that another embodiment of the impactor 10 may be formedwithout the hollow passage 54 for use with the liner-engaging head 150.

It will also be appreciated that the base portions of the differentengaging heads described above in their various embodiments, i.e.engaging heads and liner-engaging heads and their respective varyingembodiments, may have a common configuration such that they may engagethe same impactor. The common configuration allows engaging heads ofdifferent sizes and types to be used interchangeably on the sameimpactor. For example, different patients and circumstances may requiredifferent sized acetabular shells that may not be determined untilduring surgery. The common configuration of the engaging headsfacilitates the process by providing a single impactor with a pluralityof engaging heads and liner-engaging heads.

FIG. 10 illustrates another embodiment of an impactor 170. An optionalarm 172 may be coupled to an elongated body 174. The arm 172 maycomprise an extended portion 176 and a handle 178. The arm 172 may beremovably coupled by means of a threaded portion (not shown) on the endof the extended portion 176 that may rotatably engage a threaded bore180 on the elongated body 174. The arm 172 may assist the surgeon inpositioning the impactor 174 during surgery as is known in the art.

In accordance with the features and combinations described above, auseful method of implanting an acetabular shell may include the stepsof:

-   -   (a) incising a hip with a minimally invasive incision to expose        the acetabulum;    -   (b) preparing the acetabulum;    -   (c) providing an impactor having an elongate body, a head and a        coupler end, the elongate body further comprising a bent portion        and a hollow passage;    -   (d) installing an engaging head onto the coupler end;    -   (e) securing an acetabular shell to the engaging head by a        subatmospheric pressure;    -   (f) positioning the shell into the acetabulum; and    -   (g) applying an impaction force to the head in order to implant        the shell into the acetabulum.

It will be understood that the structure disclosed herein may form oneembodiment of a means for removably attaching an engaging head to anelongate body in a pressure-maintaining manner, such that any one of aplurality of engaging heads can be attached to the elongate body forinstalling surgical implants of different sizes. It should beappreciated that any structure, apparatus or system for removablyattaching an engaging head which performs functions the same as, orequivalent to, those disclosed herein are intended to fall within thescope of a means for removably attaching an engaging head in apressure-maintaining manner, including those structures, apparatus orsystems for removably attaching an engaging head which are presentlyknown, or which may become available in the future. Anything whichfunctions the same as, or equivalently to, a means for removablyattaching an engaging head in a pressure-maintaining manner falls withinthe scope of this element.

It will be appreciated that the elongate body 12 having a bent portionas disclosed herein is merely one example of a means for positioning anacetabular shell through a minimally invasive incision, and it should beappreciated that any structure, apparatus or system for positioning anacetabular shell through a minimally invasive incision which performsfunctions the same as, or equivalent to, those disclosed herein areintended to fall within the scope of a means for positioning anacetabular shell through a minimally invasive incision, including thosestructures, apparatus or systems for positioning an acetabular shellthrough a minimally invasive incision which are presently known, orwhich may become available in the future. Anything which functions thesame as, or equivalently to, a means for positioning an acetabular shellthrough a minimally invasive incision falls within the scope of thiselement.

It will be appreciated that the head 16 disclosed herein is merely oneexample of a means for receiving an impaction force, and it should beappreciated that any structure, apparatus or system for receiving animpaction force which performs functions the same as, or equivalent to,those disclosed herein are intended to fall within the scope of a meansfor receiving an impaction force, including those structures, apparatusor systems for receiving an impaction force which are presently known,or which may become available in the future. Anything which functionsthe same as, or equivalently to, a means for receiving an impactionforce falls within the scope of this element.

It will be appreciated that the coupler end 14 as disclosed herein ismerely one example of a means for selectively engaging an engaging headby a pressure-maintaining seal, and it should be appreciated that anystructure, apparatus or system for selectively engaging an engaging headby a pressure-maintaining seal which performs functions the same as, orequivalent to, those disclosed herein are intended to fall within thescope of a means for selectively engaging an engaging head by apressure- maintaining seal, including those structures, apparatus orsystems for selectively engaging an engaging head by apressure-maintaining seal which are presently known, or which may becomeavailable in the future. Anything which functions the same as, orequivalently to, a means for selectively engaging an engaging head by apressure-maintaining seal falls within the scope of this element.

It will be appreciated that the hollow passage 54 disclosed herein ismerely one example of a means for forming a subatmospheric pressure, andit should be appreciated that any structure, apparatus or system forforming a subatmospheric pressure which performs functions the same as,or equivalent to, those disclosed herein are intended to fall within thescope of a means for forming a subatmospheric pressure, including thosestructures, apparatus or systems for forming a subatmospheric pressurewhich are presently known, or which may become available in the future.Anything which functions the same as, or equivalently to, a means forforming a subatmospheric pressure falls within the scope of thiselement.

It will be appreciated that the port 42 herein is merely one example ofa means for breaking a subatmospheric pressure, and it should beappreciated that any structure, apparatus or system for breaking asubatmospheric pressure which performs functions the same as, orequivalent to, those disclosed herein are intended to fall within thescope of a means for breaking a subatmospheric pressure, including thosestructures, apparatus or systems for breaking a subatmospheric pressurewhich are presently known, or which may become available in the future.Anything which functions the same as, or equivalently to, a means forbreaking a subatmospheric pressure falls within the scope of thiselement.

Those having ordinary skill in the relevant art will appreciate theadvantages provide by the features of the present disclosure. Forexample, it is a feature of the present disclosure to provide anacetabular shell impactor with no moving parts. Another feature of thepresent disclosure to provide an acetabular shell impactor that utilizesa production of subatmospheric pressure to hold the acetabular shell onan engaging head of the impactor, without the need for an externalsubatmospheric pressure producing source. It is a further feature of thepresent disclosure, in accordance with one aspect thereof, to provide anacetabular shell impactor having interchangeable engaging heads tofacilitate a hip replacement surgery. It is still another feature of thepresent disclosure to provide an acetabular shell impactor havinginterchangeable engaging heads and interchangeable liner-engaging heads.

In the foregoing Detailed Description, various features of the presentdisclosure are grouped together in a single embodiment for the purposeof streamlining the disclosure. This method of disclosure is not to beinterpreted as reflecting an intention that the claimed disclosurerequires more features than are expressly recited in each claim. Rather,as the following claims reflect, inventive aspects lie in less than allfeatures of a single foregoing disclosed embodiment. Thus, the followingclaims are hereby incorporated into this Detailed Description by thisreference, with each claim standing on its own as a separate embodimentof the present disclosure.

It is to be understood that the above-described arrangements are onlyillustrative of the application of the principles of the presentdisclosure. Numerous modifications and alternative arrangements may bedevised by those skilled in the art without departing from the spiritand scope of the present disclosure and the appended claims are intendedto cover such modifications and arrangements. Thus, while the presentdisclosure has been shown in the drawings and described above withparticularity and detail, it will be apparent to those of ordinary skillin the art that numerous modifications, including, but not limited to,variations in size, materials, shape, form, function and manner ofoperation, assembly and use may be made without departing from theprinciples and concepts set forth herein.

1. A method of attaching an implant to an impactor, said methodcomprising the steps of: (a) joining said implant and said impactor; (b)forming a pressure-maintaining region between said implant and saidimpactor; and (c) holding said implant on said impactor at least in partby a sub-atmospheric pressure in said region created when said impactoris moved in a direction away from said implant.
 2. The method of claim1, wherein step (b) comprises sealing a port on said impactor with apart of a user's body.
 3. The method of claim 1, further comprising thestep of un-sealing said port to break said sub-atmospheric pressure andrelease said implant.
 4. The method of claim 1, further comprisingjoining a removable engaging head with said impactor, said engaging headbeing configured to engage said implant in a pressure-maintainingmanner.
 5. A method of attaching an implant to an impactor, said methodcomprising the steps of: (a) joining said implant and said impactortogether at a first position; (b) forming a pressure-maintaining regionbetween said implant and said impactor; and (c) maintaining saidpressure-maintaining region at an atmospheric pressure when said implantis at said first position.
 6. The method of claim 5, further comprisingforming a sub-atmospheric pressure in said pressure-maintaining regionby moving said implant from said first position.
 7. The method of claim5, wherein step (b) comprises sealing a port on said impactor with apart of a user's body.
 8. The method of claim 7, further comprising thestep of un-sealing said port to break said sub-atmospheric pressure andrelease said implant.
 9. The method of claim 5, further comprisingjoining a removable engaging head with said impactor, said engaging headbeing configured to engage said implant in a pressure-maintainingmanner.
 10. A method of attaching an implant to an impactor, said methodcomprising the steps of: (a) joining a removable engaging head with saidimpactor; (b) joining said implant with said removable engaging head;and (c) forming a pressure-maintaining region between said implant, saidremovable engaging head and said impactor.
 11. The method of claim 10,wherein step (c) comprises sealing a port on said impactor with a partof a user's body.
 12. The method of claim 10, further comprising thestep of holding said implant on said impactor at least in part by asub-atmospheric pressure in said region created when said impactor ismoved in a direction away from said implant.
 13. The method of claim 11,further comprising the step of un-sealing said port to break saidsub-atmospheric pressure and release said implant.
 14. The method ofclaim 10, wherein step (a) comprises selecting said removable engaginghead from a plurality of engaging heads having different sizes.
 15. Themethod of claim 10, further comprising the step of selecting saidimplant from a plurality of implants having different sizes.
 16. Themethod of claim 10, wherein step (a) comprises inserting an extensionmember of said impactor into a recessed portion of said engaging head.17. The method of claim 16, further comprising engaging at least oneresilient member on said extension member with an annular locking grooveformed in the recessed portion.
 18. The method of claim 10, furthercomprising the step of forming a friction fit between the engaging headand the impactor.
 19. The method of claim 10, further comprising thestep of forming a friction fit between the implant and the engaginghead.
 20. The method of claim 10, wherein step (a) further comprises thestep of abutting a base portion of said engaging head with an annularflange on said impactor.